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Bert
Super Administrator
Posts: 2821
Registered: 12-3-2004
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Mood: " I think we are all going to die. I think that love is an illusion. We are flawed, my darling".
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Some commercial operations do use a large and a small size together. 2 sizes are sufficient, pick a smaller sized one that fits more or less into the
interstices of your larger sized media.
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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Bert
Super Administrator
Posts: 2821
Registered: 12-3-2004
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Mood: " I think we are all going to die. I think that love is an illusion. We are flawed, my darling".
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First time, some heavy walled PVC pipe, I made end caps of plywood with melamine counter top material laminated onto both sides. I drilled and tapped
the PVC for machine screws to hold the ends on, and would wrap a couple of turns of electrical tape tightly over the seam to keep dust from escaping.
Media was several rolls of USA 5 cent coins (nickels).
Later, PVC pipe with couplers and rubber band caps as many still do. Worked better, was larger, did not wear out threads in soft plastic by repeated
opening and closing. Media was at times cast Lead cylinders, brass rods, ball bearings and other things I tried.
This was all before anyone but NASA was using Digital cameras, no pictures.
Might still have those jars somewhere. If needed, I now would use an Eloxite supplied Lortone 12 lb. rock polisher and Coors ceramic media. Have not
needed to for several many years, so I use the rock polisher with stainless steel pin media to clean cartridge brass instead.
[Edited on 18-10-2017 by Bert]
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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Fulmen
International Hazard
Posts: 1716
Registered: 24-9-2005
Member Is Offline
Mood: Bored
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That should end up somewhere around a 1:7 ratio for spheres. For soft media you would probably end up with excessive wear, but it might work for
harder materials.
The cement plant I worked at used a wide range of sizes in their mills, but I never had anything to do with that part of the operation so I don't know
why or which size distribution they used. But IIRC it was in the 1-3" range. Wear would probably be part of the reason.
We're not banging rocks together here. We know how to put a man back together.
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RogueRose
International Hazard
Posts: 1592
Registered: 16-6-2014
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I was looking at some router bits and these seem to be exactly what I am looking for as they make them in up to 2" diameter - round nose with a
carbide tipped blades which I'm sure will cut into graphite and most likely aluminum.
I plan on using a drill press so I can have speeds of 600rpm, 1400 rpm and 3200 rpm.
What do you think of these bits. These are inexpensive Chinese bits and the "brand name" ones cost 3-6 times as much.
https://www.amazon.com/uxcell-1-inch-Cutting-2-Flute-Carbide...
https://www.amazon.com/Uxcell-Double-Router-4-Inch-Standard/...
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Twospoons
International Hazard
Posts: 1324
Registered: 26-7-2004
Location: Middle Earth
Member Is Offline
Mood: A trace of hope...
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For what you want to do they should be just fine. For use with aluminium use a coolant/lubricant such as kerosene while cutting. I'd use the slower
speed for bits that size.
Helicopter: "helico" -> spiral, "pter" -> with wings
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wg48
National Hazard
Posts: 821
Registered: 21-11-2015
Member Is Offline
Mood: No Mood
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I have tried to use those on steel and broke off bits of the tungsten carbide. They have no rack angle and may be a hard but brittle grade of tungsten
carbide. I tried drilling out a pilot hole as the centre part makes slow progress. Possibly if my drill press had less wobble and I had advanced with
less pressure I may have been successful. I was on my slowest speed, which is about 250 rpm. I used drops of oil.
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Twospoons
International Hazard
Posts: 1324
Registered: 26-7-2004
Location: Middle Earth
Member Is Offline
Mood: A trace of hope...
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I'd recommend drilling a pilot hole too, as big as you can. wg48's experience with steel does not surprise me, but i've used router bits on aluminium
successfully - ali is really quite soft.
Helicopter: "helico" -> spiral, "pter" -> with wings
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Fyndium
International Hazard
Posts: 1192
Registered: 12-7-2020
Location: Not in USA
Member Is Offline
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I've tried to look for some info about the matter, but could find limited data so far.
If one wants to grind down organic and non-organic inert materials, what would be ideal grinding media for minimum contamination? There are sites that
advertise 316SS balls for pharmaceutical powder milling, and while being inert, it is not too hard, so could there be a contamination issue? Most
articles regard about minerals, ores, metals and other hard materials, but few if none on organic materials. The runtime for fining and blending
organic materials are much shorter than crushing rocks, so it could be beneficial.
For example this source states that a very small media would be preferable.
https://www.slideshare.net/unionprocess/how-to-select-the-ri...
I have had this clumping issue multiple times which has an effect on synthesis efficiency and I though ball mill would be ideal method to make fine
powders. Starting, but not limited to, desiccants like magnesium sulfate, and as well many reagents that dry into rocky formations and take a lot of
effort to fine them up by hand, with huge dusting issues, and when used for synthesis, these clumps will dissolve at very slow and uncontrolled rate
and will block funnels.
Also the size of the media bothers me. Smaller balls like 4-6mm were mentioned to be good for faster and finer result, while larger balls are for
fining bigger chunks. I'm not sure which size balls to order, but the feed is generally already pretty fine, with larger particles up to few mm size
at most.
Also, are these devices of any good for such purpose?
https://www.ebay.com/itm/133439034077
[Edited on 27-6-2021 by Fyndium]
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